With the substantial increase of digital components in the mobile market, power consumption has become a significant limiting factor in the practically achievable operating frequencies of integrated circuits. Circuit design is based on the number of computations. Each computation produces a discharge in capacitance. At each discharge, dynamic power is consumed with standard threshold voltage (VTH) transistors.
One major factor of power consumption is dynamic power, which is the active power consumed while the chip is operating. Dynamic power is consumed only when the circuit is operating and only where actual nodes of the circuit are being toggled (e.g., charged/discharged). Another major factor of power consumption is leakage power. As long as the circuit is powered on, leakage power is consumed even if the circuit is not operating.
Some conventional solutions for reducing power consumption have proposed using transistors with a threshold voltage that is less than the standard threshold voltage. On one hand, lower VTH transistors increase the speed of circuits. On the other hand, their leakage is substantially larger (one order of magnitude or more) than standard transistor leakage. This increased leakage factors in substantially in the overall power consumptions of the final product. As such, these transistors need to be used such that their cumulative leakage power does not render the mobile device unusable (e.g., running too hot or draining the battery too quickly).